The present invention concerns foundations for buildings, such as houses, warehouses and other medium to small sized structures. In particular, the invention concerns a method and components for a below-ground building foundation.
A typical residential structure is supported on a foundation buried below the frost line. In most cases, poured concrete is the material of choice for these foundations. A typical foundation for a residential home is depicted in FIGS. 1 and 2. The foundation 10 is formed around the perimeter of the home layout. In a typical procedure, a trench is dug into the ground G below the frost line, typically to a depth of three feet. A excavator is used to excavate and dig the trench around the foundation perimeter. In the next step, concrete ready-mix trucks deliver concrete to the building site. This concrete is poured into the prepared trenches to form the footing 11. The concrete footing is usually poured to a height of two feet around the entire perimeter of the foundation. The poured concrete is then given a day to cure before subsequent steps are undertaken.
Once the concrete footing 11 has cured, concrete block and cement is again delivered to the building site along with mortar sand. A block mason then installs the concrete or line block 12 on the footing 11. This line block 12 is usually provided in 16-inch lengths. Consequently, several such blocks must be laid by the block mason around the perimeter of the foundation. As shown in FIG. 2, the line blocks 12 are generally centrally situated over the footing 11. Then, additional concrete blocks 13 are installed by the block mason. These blocks 13 typically form the brick ledge, providing about a 4".times.4" ledge for orienting subsequent layers of brick for the exterior of the home. As with the line blocks 12, the brick ledge blocks 13 are provided in 16-inch lengths.
Typically, the mortar joints between the concrete blocks are allowed to cure for about one day. Laying of the line and brick ledge blocks is very time consuming, even for a skilled brick mason, often taking two days to complete for a modest residential foundation. Moreover, mortar joints are created along the entire foundation perimeter between the footing 11 and the line blocks 12, between each of the line blocks, between the line blocks and the brick ledge blocks 13, and between adjacent ledge blocks. Statistically, some of the many mortar joints will erode, which may eventually lead to problems with the foundation.
Once the line blocks 12 and brick ledge blocks 13 are laid, the mortar joints are allowed to cure for about a day. Afterwards, an excavator backfills the outer perimeter of the foundation to grade. Loose base material, such as sand or gravel 14, is used to fill the interior of the foundation to provide a base for the floor slab 15. Typically, the slab 15 is also poured concrete. The sand 14 also fills the open portion of the trench behind the blocks 12 and 13. After these steps are completed, the excess sand, block material, cement bags and block skids are cleaned up.
For a typical residential home the process of preparing the foundation can take four to five days. In addition, up to seven different laborers or contractors can be involved to operate the excavator and backfill excavator, deliver the ready-mix, concrete block and mortar, pour the concrete, lay the masonry block and perform various clean up tasks.
Another difficulty arises in the use of poured concrete. In some instances, it is difficult to control the depth, width and height of the poured media. Irregularities in the concrete footing 11 can often be corrected by the block mason when laying the concrete line 12 and brick ledge 13; however, the mortar joints themselves can be subject to irregularities. The make up of the soil itself can pose some difficulties to a poured concrete foundation. For some soils, a rigid form must be placed within the trench to provide a viable channel into which the concrete is poured. Weather also plays a part in the construction of poured concrete foundations. Moisture and temperature can affect the curing time for the concrete and mortar joints. Excessive rain or below-freezing temperatures can delay pouring concrete.
There is always a need for components and methods that streamline the process of preparing a building foundation. A quicker process can lead to significant savings in labor charges, particularly if the number of subcontractors can be reduced. Decreasing the time for building a foundation can also avoid weather-related problems that may delay various steps of the traditional process.